This invention relates to a process for preparing diarylcarbonates, such as diphenylcarbonate.
The reaction of phenols with phosgene is well known in the prior art. In the reactions employing phosgene, a phenol is heated in the presence of a homogeneous catalyst such as an inorganic base, with or without a solvent. Next, the mixture is gassed with phosgene. If a one to one mole ratio of phenol to phosgene is used, the reaction produces the phenylchloroformate. But if two or more equivalents of the phenol are employed, the reaction yields a diarylcarbonate. These methods are not without difficulties, however, because the homogeneous catalyst must be separated from the product in another step. Moreover, it is known that traces of the catalyst remain in the product despite the great care placed in removing the contaminants. What is needed, therefore, is an efficient method of producing diarylcarbonates which alleviates these problems.